1. The veins that bridge from the brain to the dura, which is fixed to the inside of the skull, are stretched and, exceeding their elasticity, tear open and bleed, creating the subdural hematoma or subarachnoid hemorrhages or characteristics of the syndrome.
    
2. The brain strikes the inner surfaces of the skull, causing direct trauma to the brain substance itself.
    
3. The deeper structures of the brain, the axons, can be broken, shearing off during the commotion to the brain.
    
4. The lack of oxygen during shaking causes further irreversible damage to the brain substance.
    
5. Damaged nerve cells release chemicals which add both to oxygen deprivation to the brain and also cause direct further damage to the brain cells.

The combined effect is massive traumatic destruction of the brain tissue, leading to immediate brain swelling and causing enormous increases in the pressure within the skull. This swelling compounds the problem, since swelling causes compression of the blood vessels and decreases the oxygen supply to the brain.

It is these injuries to the brain, not the bleeding under the Dura or the Arachnoid Membranes that cause the signs, symptoms, and course of Shaken Baby/Shaken Impact Syndrome.

Concomitant with the destruction of the brain tissue are other injuries. The most significant of these are the retinal hemorrhages. There are a number of theories to explain retinal hemorrhages in SBS/SIS. One states that they are the result of transmitted pressure within the skull. The argument against this is that retinal hemorrhages occur with much less frequency in infants whose brain injuries are due to accidental causes with similar increased pressures within the skull, such as those resulting from motor vehicle accidents. Another theory is that retinal hemorrhages occur because shaking causes disruption of the layers of the retina. There are 10 layers on the retina, all richly supplied with blood vessels. Proponents of this theory state that when these layers are subjected to the lines of force associated with shaking, they slide across one another, stretching these vessels so that they also shear and bleed.

The retinal hemorrhages seen in SBS/SIS are variable ranging from a few scattered hemorrhages to extensive hemorrhages involving multiple layers of the retina. Retinal hemorrhages seen in other conditions are usually closer to the surface, so-called preretinal hemorrhages, and resolve quickly. Retinal hemorrhages are not seen as the result of cardiopulmonary resuscitation or accidental short falls.

A number of other lesions are variable findings in SBS/SIS. These include skull fractures resulting from the impact when the infant is thrown against a hard or soft surface; fractures of the posterior arcs of the ribs near the spine due to the levering of the fingers of the hands of the perpetrator while holding the baby during shaking; fractures of the clavicles (collarbone); and fractures of the long bones. Long bone fractures are attributed to the flailing of the arms and legs during shaking. Bruising of the skin of the head, face and body may also occur. It is uncommon to see injuries to the bones, interspinous ligaments and muscles of the neck, probably due to the underdevelopment of these structures in the infant. It is also uncommon to see injuries to the spinal cord in cases of SBS/SIS.

It is important to state that there is no evidence to support the concept that re-bleeding of an older subdural hematoma can result from trivial injury and cause an infant to suddenly collapse and die. The subdural bleeding is only significant in that it is a marker for the traumatic episode to the brain that produces all the clinical signs and symptoms. Even of such a re-bleeding should occur, it does not cause traumatic injury to the brain.

There is no evidence that the findings in SBS/SIS can result from accidental falls in the home, including falls down stairs, off beds or tables, or from caretaker's arms. SBS/SIS results from a violent inflicted injury producing immediate signs and symptoms.

Robert M. Reece, M.D.
Robert H. Kirschner, M.D.

 Costs Associated with SBS

Other Facts about SBS

The initial costs of hospitalization can easily be over $150,000. The Texas Brain Injury Association estimates that permanent brain injury costs could well reach $3 million dollars for a lifetime of care. The abusers rarely pay any of these costs. Victim families, taxpayers and insurance companies are responsible for these; rehabilitation, medical, special education and living expenses.

Children who continue receiving medical treatment and in-home nursing are typically at a cost of about $180,000 a year.

Some experts believe the costs could be as much as $15 million over a lifetime.

50% to 75% of adults and teenagers do not know that shaking a baby could be dangerous. The number of shaken baby survivors has not been documented. The Centers for Disease Control and Prevention estimate that abuse and neglect annually kill 5.4 out of every 100,000 children under age four. CDC also estimates that misclassification of childhood deaths probably means that this figure should be 11.6 out of every 100,000….more than the country's overall murder rate of 10 per 100,000. At least 2000 children die from abuse or neglect each year and another 18,000 are left permanently disabled. Most are under the age of four. Shaken baby syndrome accounts for an estimated 10-12% of all deaths due to abuse or neglect. Approximately ¼ of all children inflicted with SBS die and 41% of SBS victims are under the age of one. Experts say 1,000-1,500 cases of SBS occur each year in the United States, but the true number of cases is unknown because of misdiagnoses and underreporting. A baby can fall 3 stories and not get as seriously injured as a shaken baby. When a child is shaken in anger and frustration, the force is multiplied 5-10 times more than it would be if the child had simply tripped or fallen. If a baby has been shaken, it is important that it be taken to the hospital right away. Tell the doctor the baby was shaken so proper medical attention may be given.